GeoExchange / Thermal Energy Storage Systems Reduce Overall Energy Use and Peak Demand

Peak Electrical Demand is a Problem! Satellite photo of North America at night during the blackout of 2003

GeoExchange / Thermal Energy Storage (TES) What is Earth Energy? (AKA GeoExchange TM, geothermal, ground-source, etc.) What is Thermal Energy Storage (TES)? Integrating Earth Energy with TES What are the benefits? What applications work with GEO/TES?

5% absorbed by clouds 19% reflected by clouds 8% reflected by surface 21% absorbed by water vapor, dust 47% absorbed by ground Source: U.S. Dept. of Energy Up to 100% of the heat taken from the building can be absorbed by the earth …and taken out when needed BuildingGeoExchangeGeoExchange

Earth Loops Pipe ready to install in lake Drilling for vertical loop Horizontal earth loop Different types of loops are equally effective. Type of loop used depends on location and site conditions

Long History of Thermal Ice Storage A ton of ice absorbs 12,000 btuh of heat energy for 24 hours for it to melt (909 kg absorbs kW for 24 hours) Ice harvested in winter was used to provide cooling in summer

Today’s “Ice Shed” Today's “ice shed” stores ice made by a chiller at off-peak times to provide the next day’s air conditioning. Each tank stores 160 ton-hours of cooling Tanks can be buried outside of the building or located in the mechanical room

Ideal Building for GeoExchange / TES Mission Centre Offices, Kelowna, BC, Canada 45,000 sq. ft. (4,200 m 2 ) office building Heat loss when unoccupied in winter: 503,000 btuh (148 kW) Heat gain when occupied in winter: 91,000 btuh (27 kW) Heat gain in summer:1,390,000 btuh (116 tons or 407 kW)

Conventional Equipment 120 ton roof-mounted chiller & gas boilers would typically be specified for this type of building.

Equipment Used GeoExchange / TES System Low temperature fluid-fluid heat pumps using environmentally acceptable HFC - R404A refrigerant Efficient at temperatures as low as 10 degrees F In the event of a compressor failure, multiple heat pumps & multiple circulation pumps provide redundancy “Waste heat” provides heat to building while the heat pumps are making ice for tomorrow’s cooling

Integrated System Schematic Without TES Earth loop Fluid-to-fluid heat pumps Heating & cooling fan coils

Integrated System Schematic With TES Less earth loop required with TES Ice storage Less equipment needed with TES Heating & cooling fan coils

Making Ice / Heating Building Earth loop not used Building absorbs heat from ice Ice is heat source for system

Making Ice / Storing Heat in Earth Loop Excess heat stored in the earth loop

Heating Building with Earth Loop Building takes heat from earth Earth loop is heat source Ice storage fully built

Heating & Cooling Building Simultaneously One heat pump provides both heating & cooling Cooling zones are heat source… …for heating zones Earth loop not used

Peak Cooling of Building Using TES Only Earth loop not used Heat pumps not needed Ice built during off-peak times cools building

Fluid Cooler Minimizes Cost of Earth Loop Earth loop Fluid-to fluid heat pumps Heating & cooling fan coils Ice storage Size & cost of earth loop can be minimized by using fluid cooler to maintain loop temperature

Fluid Coolers Reduce Loop Length

Snow-melt Reduces Earth Loop Length Earth loop Fluid-to fluid heat pumps Heating & cooling fan coils Size & cost of earth loop can be minimized by using fluid cooler to maintain loop temperature Ice storage Snow melt on sidewalks & driveways can be done with excess heat to minimize loop size

“Waste” Heat Melts Snow on Sidewalks ACEC Colorado 2003 Grand Conceptor Award for: Christiana Building, Ketchum, ID Waste heat from mechanical system melts snow from sidewalks Minimizes size & cost of earth loop Reduces cost & noise associated with cooling tower Increases public safety Street in Grand Rapids, MI with snow melt

GEO/TES vs Geothermal Capital Cost Geothermal System GEO/TES Equipment (heat pumps, circ. pumps, fan coils etc.) $148,000$142,000 Ice Storage Tanks - $90,000 (900 ton-hours) Fluid Cooler - $32,000 (75 ton fluid cooler) Earth Loop $260,000 (20,000’ borehole) $130,000 (10,000’ borehole) Total Installation Cost $408,000$394,000

Conventional Cooling – Electrical Load Profile Peak demand of chiller * Based on Mission Office Centre Loads

Conventional Cooling & Heating Load Profile Fossil fuel boilers heat building at night Chiller cools building during the day * Based on Mission Office Centre Loads

Conventional Heating & Ice Storage Profile Fossil fuel boiler heats building at night Chiller builds ice at night Ice cools building during the day * Based on Mission Office Centre Loads

Integrated GEO/TES - Load Profile “Free” ice cools building from night time heating “Free” heat from ice * Based on Mission Office Centre Loads

** Based on average CO 2 emissions for electricity & gas produced in Quebec, Manitoba & BC, Canada –.025 kg/kWh & kg/m3 (source: NRCan) 93% less GHG than conventional system 60% less GHG than geothermal system * Based on Mission Office Centre Loads GHG Emissions (Hydro or Nuclear Electricity)

** Based on average CO 2 emissions for electricity & gas produced in Ontario, Canada –..26 kg/kWh & kg/m3 (source: NRCan) 74% less GHG than conventional system 60% less GHG than geothermal system without TES * Based on Mission Office Centre Loads GHG Emissions (Mixed Generation Electricity)

** Based on average CO 2 emissions for electricity & gas produced in Alberta, Canada – 1.03 kg/kWh & kg/m3 (source: NRCan) 60% less GHG than geothermal system 65% less greenhouse conventional system * Based on Mission Office Centre Loads GHG Emissions (Coal Generated Electricity)

Appropriate Applications of GEO/TES Buildings with higher cooling loads than heating loads –Commercial office buildings –Schools –Industrial cooling loads Buildings with occasional high cooling loads –Churches, halls Areas where the electric utilities provide low off- peak power rates.

Geothermal Ice Arena / Ice Storage Systems Completed Projects Under Construction

Benefits of GEO/TES Integration Lower energy demand & consumption –Less electricity used for refrigeration –Elimination of fossil fuels for heating Lower energy cost –Lower energy use –Use of less expensive off-peak energy Lower operating & maintenance costs –Less equipment, no moving parts in ice storage tanks Lower GHG emissions Lower capital cost –Less equipment, shorter earth loop Reliability with built in redundancy & storage